In a manufacturing process of semiconductor devices, a semiconductor element is formed in each rectangular region of a semiconductor substrate which is surrounded by regions for forming dicing lines. Then, the semiconductor substrate is divided into chips along dicing lines.
Broadly speaking, two methods, i.e., a blade dicing and a laser dicing are known as a method for dividing a semiconductor substrate into chips.
According to the blade dicing, a semiconductor substrate is mechanically cut using a diamond blade. The blade dicing has a problem that chipping may occur inevitably. The blade dicing has another problem that a margin is required for a distance between a blade and a chip end so that a width of a dicing line may be increased.
In a method of laser dicing, a surface of a semiconductor substrate is irradiated with laser light, and a groove is formed on the surface of the semiconductor substrate by ablation. Then, the semiconductor substrate is separated into chips by breaking from the groove as a starting point. In another method of laser dicing, an interior of a semiconductor substrate is irradiated with laser light, and a modified layer is formed in the semiconductor substrate. Then, the semiconductor substrate is separated into chips by breaking from the modified layer.
According to the laser dicing, a width of a dicing line can be reduced as compared with the blade dicing.
In any one of the methods, however, a distortion caused at the time of dividing remains in a side surface portion of a divided chip. Hence, a stress of resin to be molded can occur so that reliability of a chip-state semiconductor device may be deteriorated. In order to avoid the problem, it is necessary to add a process to remove a distortion remained in the side surface portion of the divided chip.